Mobile communication devices, such as cellular telephones, transmit and/or receive data using various protocols to communicate remotely. Other portable devices such as laptop computers, tablet computers, portable game consoles and even watches may also include components that receive and transmit data, which makes them further examples of communication devices that are mobile. Such mobile communication devices generally include a subscriber identity/identification module (SIM) card, which is an integrated circuit used to store codes that identify and authenticate subscribers across mobile communication networks.
A “subscription” may include services to which the subscriber by way of a mobile device has access. For example, a telephone number and the communications using that number are part of a subscription accessed using a SIM card. Subscriptions may use various communication standards, such as long term evolution (LTE), global system for mobile communications (GSM), general packet radio service (GPRS), enhanced data rates for GSM evolution (EDGE), universal mobile telecommunications system (UMTS), generic radio access network (GRAN), evolution-data optimized (1×/DO), and wideband code division multiple access (WCDMA) and code division multiple access (CDMA) to communicate across mobile communication networks.
Some mobile devices may include more than one SIM card in order to maintain more than one subscription. For example, dual SIM mobile devices include two SIM cards and quad SIM mobile devices include four SIM cards. In this way, a single mobile device may use different telephone numbers and maintain separate bills. Also, by using multiple SIM cards a user my keep business subscriptions separate from personal subscriptions, take advantage of different pricing/service plans or have an additional SIM card specific to a another country or region.
While having multiple SIM cards in one device has its advantages, dual SIM mobile devices consume more power than their single SIM counterparts, and quad SIM mobile devices tend to consume significantly more power than dual SIM mobile devices, which reduces their performance and is generally undesirable. Configuring dual SIM mobile devices to have two SIM cards that use a common radio frequency (RF) circuit (referred to as an “RF chain”) to communicate reduces the number of transceivers to one, which may save power. Similarly, Quad-SIM mobile devices may have just two RF chains to support the four SIM cards (i.e., enable wireless communications via the subscriptions supported by each of the SIM cards). However, such configurations mean that when one of the subscriptions starts using an RF chain for a long duration, there is a high likelihood that another subscription on that same RF chain may enter an out-of-service state.